Most inboard and outboard power motors have bladed propellers that are mounted and retained on rotating propeller shafts by a releasable securing mechanism, usually castellated nuts threaded on the propeller shaft where one of the castellated openings is arranged to receive a cotter pin, for example, that is inserted in a transverse opening provided in the shaft. An arrangement such as this prevents retrograde movement of the castellated nut so as to assure positive retention of the propeller on the shaft during use.
Although such an arrangement is very effective to prevent the accidental loss of the propeller from the shaft during use, it does make it quite easy for thieves to quickly remove and appropriate the propeller when the motor is left unattended. When a propeller is stolen, not only is the owner faced with purchasing a replacement which is usually quite costly, but there are times when the theft takes place at locations where trips can be spoiled simply because there is no way the boat can be operated without a propeller and a replacement propeller is just not readily available.
In view of the foregoing, it is appreciated that there is a need for some type of locking device to prevent unauthorized removal of a marine propeller. Various propeller locks have been proposed in the past. Some of the devices are designed to remain in place during regular use of the propeller and examples thereof are disclosed in U.S. Pat. Nos. 3,732,033 and 3,981,617. Other propeller security devices are found in U.S. Pat. Nos. 3,759,076, 3,981,165 and 4,257,247. The latter devices are of the type which must be removed during use of the propeller drive system. Although the locking devices disclosed in the foregoing U.S. patents are likely to be effective, they are, for the most part, quite complicated and thus rather expensive to manufacture. Thus there is a need to provide a simple yet highly effective device for preventing the theft of marine propellers. The need is for a device which is both strong and durable, economical to manufacture, and easy to use.